Psoriasis - Risk Factors

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Highlights	Diagnosis	Managing Psoriasis
Introduction	Treatment	Outlook
Types of Psoriasis	Topical Medications	Resources
Causes	Systemic Medications	References
Risk Factors	Phototherapy

Genetic Factors

A combination of genes is involved with increasing a person's susceptibility to the conditions leading to psoriasis. However, researchers are still unsure as to exactly how the disease is inherited.

HLA Molecules. The processes leading to all autoimmune diseases involve the human leukocyte antigens (HLA), a group of protein markers found on cells. Most immune disorders are associated with problems in how the body reacts to these different protein markers or antigens. However, other genetic and environmental factors are required to actually trigger the disease.

Four key genes (named PSOR 1 - 4) seem to be involved with psoriasis. Certain variations or changes in these genes may increase the risk of psoriasis. These same variations linked to psoriasis and psoriatic arthritis are also associated with four autoimmune diseases: type 1 diabetes, Grave's disease, celiac disease, and rheumatoid arthritis, suggesting that all of these diseases have the same genetic basis.

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The presence of a recently identified variation in a group of genes known as LCE can protect against the development of psoriasis.

Triggers

Weather, stress, injury, infection, and medications, while not direct causes, are often important in triggering, and worsening, the psoriasis.

Weather. Cold, dry weather is a common trigger of psoriasis flare-ups. Hot, damp, sunny weather helps relieve the problem in most patients. However, some people have photosensitive psoriasis, which actually improves in winter and worsens in summer when skin is exposed to sunlight.

Stress and Strong Emotions. Stress, unexpressed anger, and emotional disorders, including depression and anxiety, are strongly associated with psoriasis flare-ups. Research has suggested that stress can trigger specific immune factors associated with psoriasis flares.

Infection. Infections caused by viruses or bacteria can trigger some cases of psoriasis. For example:

Streptococcal infections in the upper respiratory tract, such as tonsillitis, sinusitis, and strep throat, are known to trigger guttate psoriasis in children and young adults. The infections may also worsen ordinary plaque psoriasis.
Human immunodeficiency virus (HIV) is also associated with psoriasis.
An uncommon form of human papillomaviruses (HPV) called EV-HPV has been associated with psoriasis. Although EV-HPV is probably not a direct cause, it may play a role in the continuation of psoriasis. This HPV form is not the virus associated with cervical cancer and genital warts.